Deep Creek Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Deep Creek Lake State Park clear sky chart from 2005-11-06 to 2026-10-29.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	13% 9% 4 9% 6% 5% 5% 4 6% 7% 31%	149144
	Night	12% 10% 4 10% 7% 5% 5% 4 5% 7% 32%	142867
Transparency	Day	48% 8% 11% 21% 11% 2	152749
	Night	48% 8% 11% 20% 11% 2	147332
Seeing	Day	26% 19% 27% 17% 8% 3	17427
	Night	24% 19% 24% 22% 10% 1	27089

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	12% 9% 10% 15% 10% 5% 4 4 6% 6% 18%	5258
	11th to 20th	Day	8% 13% 7% 21% 9% 8% 5% 3 4 4 17%	5280
	21st to end	Day	11% 10% 5% 13% 10% 7% 6% 4 6% 6% 22%	5780
February	1st to 10th	Day	11% 13% 5% 11% 8% 5% 4 5% 6% 6% 26%	1890
	11th to 20th	Day	15% 10% 4 14% 8% 5% 6% 4 6% 7% 23%	1843
	21st to end	Day	12% 13% 6% 13% 7% 6% 5% 4 5% 4 27%	1758
March	1st to 10th	Day	13% 9% 7% 8% 5% 5% 5% 3 5% 6% 33%	5045
	11th to 20th	Day	10% 8% 4 8% 4 4 5% 4 6% 8% 38%	5090
	21st to end	Day	12% 10% 4 9% 6% 5% 5% 4 6% 6% 33%	5586
April	1st to 10th	Day	12% 12% 5% 9% 5% 5% 5% 4 6% 8% 30%	2451
	11th to 20th	Day	13% 11% 4 7% 4 5% 4 4 5% 7% 36%	2494
	21st to end	Day	17% 10% 3 7% 6% 4 4 3 6% 7% 32%	2672
May	1st to 10th	Day	16% 10% 3 8% 6% 6% 6% 5% 6% 8% 27%	7616
	11th to 20th	Day	18% 8% 3 7% 5% 5% 6% 5% 7% 9% 29%	7626
	21st to end	Day	22% 9% 3 7% 5% 5% 5% 4 6% 7% 30%	8886
June	1st to 10th	Day	11% 8% 3 7% 5% 6% 5% 5% 8% 8% 34%	2940
	11th to 20th	Day	13% 7% 3 8% 6% 5% 7% 5% 7% 9% 31%	2940
	21st to end	Day	11% 7% 3 6% 5% 6% 5% 5% 7% 10% 35%	2940
July	1st to 10th	Day	9% 6% 3 8% 5% 5% 5% 4 6% 8% 40%	8007
	11th to 20th	Day	9% 7% 3 8% 6% 6% 6% 5% 7% 10% 33%	7680
	21st to end	Day	11% 7% 4 8% 6% 5% 6% 5% 7% 9% 33%	8340
August	1st to 10th	Day	14% 8% 3 9% 6% 6% 7% 5% 8% 9% 24%	6014
	11th to 20th	Day	14% 8% 3 9% 6% 6% 6% 5% 7% 8% 28%	5951
	21st to end	Day	7% 4 2 6% 4 5% 6% 6% 8% 10% 41%	6135
September	1st to 10th	Day	13% 5% 3 6% 5% 5% 4 3 6% 6% 44%	2520
	11th to 20th	Day	11% 7% 3 7% 5% 4 4 4 6% 7% 41%	2372
	21st to end	Day	19% 11% 3 8% 5% 3 4 4 5% 7% 32%	2273
October	1st to 10th	Day	12% 9% 2 6% 5% 5% 4 3 5% 7% 42%	2100
	11th to 20th	Day	14% 13% 3 7% 4 4 4 4 5% 5% 38%	2100
	21st to end	Day	13% 12% 2 8% 5% 5% 4 3 5% 6% 38%	2280
November	1st to 10th	Day	9% 9% 4 6% 4 4 5% 3 5% 6% 44%	2057
	11th to 20th	Day	11% 12% 4 11% 6% 4 5% 4 7% 6% 31%	1742
	21st to end	Day	13% 15% 6% 11% 6% 5% 4 3 5% 6% 26%	1680
December	1st to 10th	Day	11% 9% 5% 18% 9% 5% 5% 4 6% 6% 22%	2680
	11th to 20th	Day	16% 13% 6% 12% 6% 6% 5% 3 4 5% 24%	3070
	21st to end	Day	14% 12% 8% 14% 6% 6% 5% 4 7% 6% 19%	4048
January	1st to 10th	Night	8% 11% 7% 19% 12% 6% 5% 4 5% 5% 18%	7635
	11th to 20th	Night	8% 11% 6% 18% 11% 6% 4 3 4 6% 22%	7680
	21st to end	Night	12% 10% 4 11% 9% 9% 6% 3 4 5% 29%	8401
February	1st to 10th	Night	11% 9% 4 12% 7% 7% 5% 4 7% 6% 29%	2730
	11th to 20th	Night	13% 10% 5% 14% 8% 6% 6% 4 5% 5% 24%	2663
	21st to end	Night	12% 11% 5% 11% 7% 5% 5% 4 5% 6% 28%	2041
March	1st to 10th	Night	14% 11% 5% 9% 6% 4 5% 3 5% 6% 33%	5028
	11th to 20th	Night	8% 9% 4 10% 4 4 4 3 6% 7% 41%	5090
	21st to end	Night	10% 10% 4 8% 5% 5% 5% 3 5% 6% 40%	5588
April	1st to 10th	Night	12% 12% 5% 9% 6% 5% 4 4 4 6% 32%	2168
	11th to 20th	Night	11% 10% 3 8% 5% 5% 5% 4 6% 7% 36%	2075
	21st to end	Night	13% 9% 3 8% 5% 5% 4 3 4 6% 38%	1964
May	1st to 10th	Night	18% 10% 4 8% 6% 5% 5% 4 5% 7% 28%	5237
	11th to 20th	Night	18% 11% 3 6% 4 4 5% 4 6% 8% 30%	5234
	21st to end	Night	22% 11% 3 8% 6% 4 4 3 5% 6% 28%	5251
June	1st to 10th	Night	9% 8% 3 5% 5% 5% 5% 5% 6% 7% 41%	1680
	11th to 20th	Night	10% 6% 3 8% 6% 5% 4 5% 7% 9% 36%	1680
	21st to end	Night	9% 7% 3 6% 5% 5% 5% 4 8% 11% 37%	1680
July	1st to 10th	Night	9% 9% 3 7% 5% 5% 5% 4 6% 8% 38%	4932
	11th to 20th	Night	10% 8% 3 9% 6% 5% 5% 4 6% 8% 36%	5277
	21st to end	Night	10% 7% 3 9% 7% 5% 5% 4 6% 8% 36%	5736
August	1st to 10th	Night	14% 8% 3 8% 6% 6% 6% 5% 7% 10% 27%	4135
	11th to 20th	Night	14% 11% 3 9% 6% 5% 5% 4 5% 6% 32%	4095
	21st to end	Night	7% 6% 2 7% 5% 5% 4 4 6% 9% 45%	4930
September	1st to 10th	Night	12% 7% 2 6% 4 4 4 4 5% 7% 46%	2100
	11th to 20th	Night	10% 7% 2 7% 4 4 3 3 5% 7% 47%	2244
	21st to end	Night	17% 10% 3 7% 4 5% 5% 3 5% 6% 35%	2346
October	1st to 10th	Night	14% 8% 2 5% 4 5% 4 3 4 6% 45%	2520
	11th to 20th	Night	12% 10% 2 7% 4 4 4 4 5% 7% 42%	2520
	21st to end	Night	14% 11% 3 6% 5% 5% 3 3 4 6% 40%	2737
November	1st to 10th	Night	9% 10% 3 7% 5% 5% 4 3 4 6% 44%	2461
	11th to 20th	Night	12% 11% 5% 9% 6% 5% 5% 4 5% 6% 31%	2872
	21st to end	Night	12% 11% 6% 12% 6% 5% 6% 3 5% 5% 29%	2940
December	1st to 10th	Night	10% 10% 5% 18% 6% 5% 6% 4 7% 5% 24%	4720
	11th to 20th	Night	14% 10% 5% 15% 6% 6% 5% 3 5% 6% 24%	5345
	21st to end	Night	12% 13% 8% 16% 8% 6% 6% 5% 4 5% 18%	7132

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	61% 9% 9% 14% 6% 1	5259
	11th to 20th	Day	69% 6% 5% 10% 8% 2	5280
	21st to end	Day	57% 7% 12% 15% 8% 1	5780
February	1st to 10th	Day	55% 9% 9% 16% 10%	1890
	11th to 20th	Day	58% 8% 11% 13% 10%	1852
	21st to end	Day	56% 9% 9% 15% 9% 2	1758
March	1st to 10th	Day	49% 6% 9% 21% 11% 4	5045
	11th to 20th	Day	39% 9% 12% 27% 10% 3	5090
	21st to end	Day	48% 7% 10% 19% 15% 2	5586
April	1st to 10th	Day	50% 9% 11% 16% 12% 2	2451
	11th to 20th	Day	46% 8% 12% 16% 16% 3	2494
	21st to end	Day	49% 7% 11% 22% 9% 1	2672
May	1st to 10th	Day	52% 8% 10% 22% 7% 2	7651
	11th to 20th	Day	48% 9% 11% 25% 6% 1	7630
	21st to end	Day	50% 9% 10% 16% 12% 3	8901
June	1st to 10th	Day	43% 10% 11% 22% 13% 1	2940
	11th to 20th	Day	45% 11% 12% 22% 10% 1	2940
	21st to end	Day	42% 11% 12% 23% 11% 1	2940
July	1st to 10th	Day	41% 8% 11% 25% 13% 2	7941
	11th to 20th	Day	43% 9% 13% 27% 7%	7611
	21st to end	Day	43% 8% 10% 23% 15% 1	8156
August	1st to 10th	Day	51% 11% 13% 18% 7%	6001
	11th to 20th	Day	49% 9% 12% 22% 7%	5990
	21st to end	Day	33% 10% 16% 28% 13% 1	6135
September	1st to 10th	Day	40% 8% 10% 20% 18% 3	2520
	11th to 20th	Day	40% 7% 10% 26% 14% 2	2372
	21st to end	Day	50% 7% 11% 18% 13% 1	2273
October	1st to 10th	Day	33% 6% 7% 26% 22% 5%	3360
	11th to 20th	Day	38% 5% 11% 21% 14% 10%	3340
	21st to end	Day	32% 5% 10% 28% 22% 3	3618
November	1st to 10th	Day	39% 7% 10% 22% 18% 5%	2057
	11th to 20th	Day	49% 9% 9% 15% 15% 3	1742
	21st to end	Day	56% 8% 11% 15% 9% 1	1680
December	1st to 10th	Day	59% 7% 13% 16% 4 1	2680
	11th to 20th	Day	61% 7% 10% 16% 7% 1	3066
	21st to end	Day	60% 9% 12% 12% 7%	4048
January	1st to 10th	Night	63% 8% 8% 13% 7% 1	7636
	11th to 20th	Night	58% 7% 11% 12% 9% 3	7680
	21st to end	Night	54% 8% 10% 18% 9% 1	8401
February	1st to 10th	Night	51% 11% 10% 17% 10% 1	2730
	11th to 20th	Night	59% 8% 10% 14% 9%	2665
	21st to end	Night	53% 10% 8% 17% 9% 3	2041
March	1st to 10th	Night	49% 7% 10% 21% 10% 2	5028
	11th to 20th	Night	39% 9% 11% 28% 9% 4	5090
	21st to end	Night	42% 7% 13% 21% 15% 2	5588
April	1st to 10th	Night	51% 8% 10% 17% 12% 2	2168
	11th to 20th	Night	45% 9% 12% 18% 13% 3	2075
	21st to end	Night	44% 7% 11% 25% 10% 2	1964
May	1st to 10th	Night	53% 8% 13% 15% 9% 2	5264
	11th to 20th	Night	47% 9% 12% 24% 8%	5235
	21st to end	Night	53% 10% 10% 16% 9% 2	5258
June	1st to 10th	Night	39% 10% 10% 24% 15% 1	1680
	11th to 20th	Night	41% 10% 14% 23% 11% 1	1680
	21st to end	Night	37% 11% 15% 23% 14% 1	1680
July	1st to 10th	Night	43% 9% 11% 24% 11% 1	4890
	11th to 20th	Night	44% 8% 14% 23% 9% 1	5226
	21st to end	Night	42% 9% 11% 21% 16% 1	5606
August	1st to 10th	Night	49% 10% 15% 19% 7%	4124
	11th to 20th	Night	50% 8% 11% 21% 10%	4122
	21st to end	Night	34% 8% 17% 30% 11% 1	4930
September	1st to 10th	Night	36% 9% 13% 22% 17% 3	2100
	11th to 20th	Night	34% 8% 11% 28% 17% 2	2244
	21st to end	Night	48% 7% 11% 18% 15% 1	2346
October	1st to 10th	Night	35% 6% 8% 28% 21% 2	4040
	11th to 20th	Night	35% 7% 9% 21% 19% 10%	4019
	21st to end	Night	33% 6% 8% 28% 20% 5%	4349
November	1st to 10th	Night	40% 7% 10% 20% 17% 5%	2461
	11th to 20th	Night	51% 8% 8% 18% 13% 3	2872
	21st to end	Night	55% 8% 10% 16% 9% 2	2940
December	1st to 10th	Night	56% 8% 13% 18% 4 1	4720
	11th to 20th	Night	58% 7% 12% 15% 7%	5348
	21st to end	Night	64% 9% 9% 11% 7%	7132

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	43% 27% 21% 5% 3	330
	11th to 20th	Day	47% 28% 20% 4 1	330
	21st to end	Day	39% 33% 24% 4 1	363
February	1st to 10th	Day	38% 30% 25% 6% 1	330
	11th to 20th	Day	53% 23% 20% 3	330
	21st to end	Day	40% 30% 25% 4 1	364
March	1st to 10th	Day	35% 27% 27% 9% 2	540
	11th to 20th	Day	38% 26% 22% 10% 3 1	540
	21st to end	Day	36% 25% 26% 11% 2	594
April	1st to 10th	Day	32% 24% 28% 12% 4	540
	11th to 20th	Day	29% 22% 29% 13% 6% 2	532
	21st to end	Day	32% 24% 25% 13% 4 1	540
May	1st to 10th	Day	33% 20% 28% 12% 4 2	543
	11th to 20th	Day	27% 21% 26% 17% 7% 2	567
	21st to end	Day	24% 17% 27% 18% 10% 5%	617
June	1st to 10th	Day	16% 19% 30% 21% 10% 4	570
	11th to 20th	Day	21% 17% 29% 19% 11% 4	570
	21st to end	Day	13% 17% 31% 24% 13% 2	570
July	1st to 10th	Day	12% 9% 30% 25% 17% 7%	565
	11th to 20th	Day	8% 11% 34% 27% 13% 6%	564
	21st to end	Day	15% 11% 29% 25% 13% 6%	620
August	1st to 10th	Day	13% 13% 29% 24% 15% 7%	566
	11th to 20th	Day	15% 10% 28% 24% 13% 9%	559
	21st to end	Day	11% 11% 27% 27% 14% 9%	627
September	1st to 10th	Day	15% 12% 25% 25% 14% 8%	570
	11th to 20th	Day	15% 8% 27% 25% 19% 7%	570
	21st to end	Day	29% 13% 25% 18% 11% 3	570
October	1st to 10th	Day	19% 13% 27% 24% 13% 3	570
	11th to 20th	Day	25% 21% 26% 18% 8% 2	570
	21st to end	Day	28% 22% 26% 16% 8% 1	615
November	1st to 10th	Day	26% 19% 29% 17% 8% 2	535
	11th to 20th	Day	31% 28% 28% 9% 4	254
	21st to end	Day	38% 27% 25% 8% 2	220
December	1st to 10th	Day	38% 30% 23% 6% 1 1	220
	11th to 20th	Day	42% 24% 25% 7% 2	220
	21st to end	Day	38% 27% 21% 11% 2	242
January	1st to 10th	Night	34% 31% 23% 9% 3	840
	11th to 20th	Night	36% 29% 23% 11% 1	840
	21st to end	Night	36% 29% 24% 10% 1	924
February	1st to 10th	Night	31% 25% 27% 15% 1	840
	11th to 20th	Night	36% 32% 24% 8%	823
	21st to end	Night	33% 29% 27% 10% 1	692
March	1st to 10th	Night	29% 25% 28% 16% 2	840
	11th to 20th	Night	33% 23% 24% 14% 5%	840
	21st to end	Night	25% 26% 31% 15% 4 1	924
April	1st to 10th	Night	25% 25% 29% 17% 3	840
	11th to 20th	Night	23% 20% 28% 20% 7%	831
	21st to end	Night	24% 18% 26% 26% 6%	704
May	1st to 10th	Night	23% 16% 27% 26% 7%	630
	11th to 20th	Night	24% 12% 26% 27% 10% 1	621
	21st to end	Night	13% 11% 24% 28% 21% 2	508
June	1st to 10th	Night	12% 12% 24% 35% 16% 1	420
	11th to 20th	Night	13% 11% 25% 32% 18% 1	420
	21st to end	Night	13% 8% 30% 33% 15% 1	420
July	1st to 10th	Night	9% 8% 23% 34% 22% 3	491
	11th to 20th	Night	8% 8% 20% 36% 24% 4	612
	21st to end	Night	10% 8% 21% 34% 25% 2	690
August	1st to 10th	Night	12% 6% 18% 38% 24% 2	627
	11th to 20th	Night	12% 7% 17% 38% 23% 3	624
	21st to end	Night	11% 7% 20% 37% 23% 3	871
September	1st to 10th	Night	15% 6% 23% 33% 20% 3	840
	11th to 20th	Night	14% 8% 18% 34% 24% 3	840
	21st to end	Night	23% 12% 19% 29% 16% 2	840
October	1st to 10th	Night	18% 13% 22% 26% 18% 3	840
	11th to 20th	Night	21% 17% 26% 25% 9% 1	840
	21st to end	Night	25% 20% 24% 22% 7% 1	913
November	1st to 10th	Night	20% 18% 27% 26% 9% 1	820
	11th to 20th	Night	30% 21% 24% 18% 6% 1	840
	21st to end	Night	29% 23% 27% 16% 3 1	840
December	1st to 10th	Night	33% 26% 23% 13% 4	840
	11th to 20th	Night	32% 28% 22% 16% 2	840
	21st to end	Night	30% 26% 26% 16% 2	924

Page generated at 2026-10-26 04:37:51. Version ac07

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